Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: question: Nomeie os singles femininos para raina tzvetkova petya nedelcheva
 ###Tabelas: CREATE TABLE pdc_premier_event_finals:_5_1_title_4_runner-ups (pdc_premier_event_finals:_5_1_title_4_runner-ups_id AUTO_INCREMENT PRIMARY KEY, Outcome VARCHAR, Year INT, Championship VARCHAR, Opponent in the final VARCHAR, Score (l) = score in legs, (s) = score in sets. VARCHAR) CREATE TABLE pool_b (pool_b_id AUTO_INCREMENT PRIMARY KEY, Date VARCHAR, Time VARCHAR, Score VARCHAR, Set 1 VARCHAR, Set 2 VARCHAR, Set 3 VARCHAR, Total VARCHAR) CREATE TABLE past_winners (past_winners_id AUTO_INCREMENT PRIMARY KEY, Year INT, Mens singles VARCHAR, Womens singles VARCHAR, Mens doubles VARCHAR, Womens doubles VARCHAR, Mixed doubles VARCHAR) CREATE TABLE most_assists (most_assists_id AUTO_INCREMENT PRIMARY KEY, Name VARCHAR, Years VARCHAR, MLS Cup INT, U.S. Open Cup INT, CONCACAF INT, Other INT, Total INT) CREATE TABLE team_roster_season_2011-2012 (team_roster_season_2011-2012_id AUTO_INCREMENT PRIMARY KEY, Shirt No INT, Nationality VARCHAR, Player VARCHAR, Birth Date VARCHAR, Height INT, Position VARCHAR)  
SELECT Womens singles FROM past_winners WHERE Womens doubles = Raina Tzvetkova Petya Nedelcheva